Tensile and flexural failure behaviors of bolted T-joint consisting of T300/BMP316 composite laminates and TC4 alloy

Abstract

T-joints are increasingly applied as the connection between vane and case in aero-engines. However, their mechanical behavior and damage mechanisms are unclear, restricting a broader range of applications. In this paper, a bolted T-joint was designed, which was composed of a T300/BMP316 laminated case and TC4 vane, followed by tensile and flexural tests to investigate the mechanical behavior. Subsequently, a progressive damage model based on continuum damage mechanics was employed to predict the bearing capacity and damage evolution of the joints. A comparison between simulation results and the tests shows that the maximum error in displacement is 6.6%, and the maximum error in load is 2.9%. The damage modes are similar, which verifies the reliability of the simulations. The results indicate that the structure reaches the tensile capacity when fiber damage extends to the whole width of the case. And the fiber damage mainly occurs on the loading side and dominates the strength of the T-joint under flexural loading. Massive matrix damage and delamination occur in the laminated case under both loading modes, which reduces the stiffness of the T-joints. Moreover, it is observed that plastic deformation extends on the flange of TC4 vane along the fillet under flexural loading, which aggravates the decrease of structural stiffness. This work is to provide references for the engineering design of the connection structure between aero-engine vanes and the case.